136 DIVERGENCE OF CHARACTER. [Chap. IV. 



history, the men of one nation or district required 

 swifter horses, whilst those of another required stronger 

 and bulkier horses. The early differences would be very 

 slight ; but, in the course of time, from the continued 

 selection of swifter horses in the one case, and of stronger 

 ones in the other, the differences would become greater, 

 and would be noted as forming two sub-breeds. Ulti- 

 mately, after the lapse of centuries, these sub-breeds 

 would become converted into two well-established and 

 distinct breeds. As the differences became greater, the 

 inferior animals with intermediate characters, being 

 neither very swift nor very strong, would not have been 

 used for breeding, and will thus have tended to disappear. 

 Here, then, we see in man's productions the action of 

 what may be called the principle of divergence, causing 

 differences, at first barely appreciable, steadily to increase, 

 and the breeds to diverge in character, both from each 

 other and from their common parent. 



But how, it may be asked, can any analogous prin- 

 ciple apply in nature ? I believe it can and does apply 

 most efficiently (though it was a long time before I saw 

 how), from the simple circumstance that the more diver- 

 sified the descendants from any one species become in 

 structure, constitution, and habits, by so much will they 

 be better enabled to seize on many and widely diver- 

 sified places in the polity of nature, and so be enabled 

 to increase in numbers. 



"We can clearly discern this in the case of animals 

 with simple habits. Take the case of a carnivorous 

 quadruped, of which the number that can be supported 

 in any country has long ago arrived at its full average. 

 If its natural power of increase be allowed to act, it can 

 succeed in increasing (the country not undergoing any 



